Loans and Allowance for Credit Losses - Collateral dependent loans (Details) - USD ($)	Dec. 31, 2024	Mar. 31, 2024
Loans and Allowance for Credit Losses
Total loans	$ 108,490,797	$ 109,032,841
Collateral
Loans and Allowance for Credit Losses
Total loans	747,426	857,191
Real estate
Loans and Allowance for Credit Losses
Total loans	349,232	407,805
Business assets
Loans and Allowance for Credit Losses
Total loans	398,194	449,386
Real estate loans | Residential
Loans and Allowance for Credit Losses
Total loans	70,552,508	69,160,096
Real estate loans | Multi-family
Loans and Allowance for Credit Losses
Total loans	1,923,762	1,909,791
Real estate loans | Commercial
Loans and Allowance for Credit Losses
Total loans	24,076,150	24,001,533
Real estate loans | Commercial | Collateral
Loans and Allowance for Credit Losses
Total loans	349,232	407,805
Real estate loans | Commercial | Real estate
Loans and Allowance for Credit Losses
Total loans	349,232	407,805
Real estate loans | Construction and land
Loans and Allowance for Credit Losses
Total loans	1,601,808	3,087,855
Real estate loans | Home equity line of credit (HELOC)
Loans and Allowance for Credit Losses
Total loans	4,465,967	4,191,076
Commercial and industrial
Loans and Allowance for Credit Losses
Total loans	4,409,370	4,889,602
Commercial and industrial | Collateral
Loans and Allowance for Credit Losses
Total loans	398,194	449,386
Commercial and industrial | Business assets
Loans and Allowance for Credit Losses
Total loans	398,194	449,386
Consumer
Loans and Allowance for Credit Losses
Total loans	$ 1,461,232	$ 1,792,888